A. Field of the Invention
The present invention relates to a method for covering an open wound. The present invention further relates to a method of preparing a cellulosic wound dressing which is antimicrobially treated and the resulting bandage.
B. Description of the Related Art
Wound dressings have been used in the medical industry for years to help heal and protect open wounds. Cellulosic bandages used in the medical industry are typically made from woven greige cloth, which is cloth that is unbleached and unfinished. The cloth is bleached to whiten the fabric, and is converted into a gauze bandage.
Ideally, cellulosic wound dressings should have certain properties to aid in proper healing of the wound. For instance, U.S. Pat. No. 5,527,271 to Shah et al. discloses a thermoplastic hydrogel impregnated composite material for wound dressings. The hydrogel is applied to the cotton gauze wound dressing to prevent the wound dressing from adhering to the wound during the healing process.
Similarly, U.S. Pat. No. 4,838,253 to Brassington et al. discloses a silicone gel coated permeable wound dressing which is prepared by coating a sheet of apertured material with a non-crosslinked silicone material and then causing it to crosslink. The disclosed wound dressings have increased absorbency as well as having properties which prevent wound dressings from adhering to the wound surface.
More importantly, however, a wound dressing should have antimicrobial properties which kill airborne bacteria upon contact with the dressing, to prevent bacteria from entering the wound and migrating through the wound dressing. Accordingly, there have been many efforts in the past to process a cellulosic wound dressing that has antimicrobial properties.
For instance, U.S. Pat. No. 4,728,323 to Matson discloses an antimicrobial wound dressing comprised of a substrate coated with an antimicrobially effective film of a silver salt. The antimicrobial wound dressing is prepared by depositing certain silver salts onto a wound dressing surface. However, the process for treating the wound dressing is rather time consuming and complex, as the antimicrobial treatment must be applied by a separate apparatus, namely a sputter coating apparatus.
EP 0 136 900 and Canadian Pat. No. 1,223,208 disclose a nonwoven fabric which possesses antimicrobial properties and is useful in the manufacture of surgical drapes. The nonwoven fabric is treated with an antimicrobial agent which has activity against a broad spectrum of Gram negative and Gram positive bacteria and which will not become inactivated by blood serum. The antimicrobial agent used is polyhexamethylene biguanide (hereinafter xe2x80x9cPHMBxe2x80x9d). As noted in the background section, PHMB has been suggested as having antimicrobial utility in the treatment of textile materials. U.S. Pat. Nos. 2,336,605; 2,990,425; 4,022,836; 2,863,919 disclose this utility.
In addition, PHMB has been used in water treatment for controlling the growth of algae as disclosed in U.S. Pat. No. 4,014,676 to Carter et al., for the treatment of dandruff as disclosed in U.S. Pat. No. 4,405,645 to Rxc3x6thlisberger et al., and as a contact lens preservative as disclosed in U.S. Pat. No. 4,758,595 to Ogunbiyi et al.
More recently, PHMB has been used in woven textile materials, such as clothing. For instance, GB 2 300 200 discloses a cellulosic substrate which is treated with a polymeric biguanide followed by an antibonding agent to confer antimicrobial properties to the cellulosic substrate. The treated substrate has an ancillary characteristic of reducing the propensity of the substrate to yellow on contact. Treated articles may be formed as shirts, underwear, uniforms, and socks, and is particularly useful for articles that become soiled and susceptible to microbial growth. It is important to note that the use of the antibonding agent helps prevent the normal reaction of PHMB to humans, had the PHMB been used alone. PHMB, if used alone to treat the article, could cause various skin disorders, such as redness, tenderness, and hives.
WO 98/18330 discloses non-leaching antimicrobial materials capable of killing microorganisms on contact, but which do not leach significant amounts of antimicrobial materials into the surrounding environment. The antimicrobial material comprises a complex of a polycationic ligand compound and a metallic material, where the polycationic compound is a polymer. In a preferred embodiment, the polymeric material is PHMB, the crosslinking agent is non-methylene bisdiglycidylaniline (hereinafter xe2x80x9cMBDGAxe2x80x9d), and the metallic material is a silver salt, wherein the silver salt is transferred from the coating to the microorganism and accumulates to toxic levels to kill the microorganism. The disclosed antimicrobial compositions can be used on various types of substrates, such as woods, metals, paper, clothing, glasses, and ceramics. In addition, the antimicrobial materials in powder form can be dispersed or dissolved in a carrier and used as a topical antiseptic, a topical dressing for a wound or a topical disinfectant. However, the disclosed composition can only be added to substrates as a surface coating. Therefore, the disclosed composition, if applied as a surface coating, would not protect migration of the bacteria throughout the wound dressing.
U.S. Pat. No. 5,019,096 to Fox, Jr. et al. discloses an infection-resistant composition for medical devices and surfaces and methods for preparing and using same. The method includes incorporating an effective amount of antimicrobial agent in a matrix comprising a polymeric component, wherein the matrix is effective to provide controlled release of the antimicrobial agent at a level sufficient to suppress infection when in contact with fluids. The antimicrobial agent is disclosed as including synergistically effective amounts of a silver salt and a biguanide. Preferably, the final coating contains from 10 to 70% by weight of the microbial agent. This composition is meant only as a coating and would not prevent microbial migration through a wound dressing.
In one aspect, the present invention provides a method of covering and protecting an open wound from microbial contamination, by dressing the wound with a cellulosic wound dressing having an antimicrobial amount of PHMB applied to the bandage.
In a further important aspect, the present invention provides a method of covering an open wound by directly contacting the wound with a cellulosic wound dressing having an antimicrobial amount of PHMB applied to the bandage, without having an intermediate layer between the antimicrobially treated bandage and the open wound.
In yet a further aspect, the present invention provides a wound dressing consisting essentially of PHMB.
In a further aspect, the present invention provides a method of manufacturing a wound dressing having antimicrobial properties. The method comprises:
A) providing at least one rolled beam of cellulosic material;
B) inserting the beam of material into an enclosed vessel;
C) adding PHMB into the vessel; and
D) circulating the PHMB for a predetermined period of time.
In a still further aspect, the present invention provides a wound dressing manufactured according to the claimed method.